Effects of Belonolaimus longicaudatus Management and Nitrogen Fertility on Turf Quality of Golf Course Fairways

Field experiments evaluated the effects of nematicide and fertility on performance of ‘Tifway 419’ bermudagrass parasitized by the sting nematode (Belonolaimus longicaudatus). Plot treatments were nontreated or nematicide (1,3-dichloropropene) treated combined with different nitrogen (N) fertilizer levels. Effects of treatments on numbers of B. longicaudatus and turf performance were compared. Nematicide consistently reduced numbers of B. longicaudatus, but fertilizer level had no effect on B. longicaudatus. Turf performance of nematicide-treated plots was improved compared with nontreated plots during both experiments. Increasing N fertilizer level improved turf performance in nematicide-treated plots in some cases, but had no effect on turf performance in nontreated plots in either experiment. Results suggest that increasing N fertilizer levels may not improve turf performance at sites infested with B. longicaudatus unless nematode management tactics are effective in reducing nematode densities.     

Alternatives to Fenamiphos for Management of Plant-Parasitic Nematodes on Bermudagrass

Plant-parasitic nematodes can be very damaging to turfgrasses. The projected cancellation of the registration for fenamiphos in the near future has generated a great deal of interest in identifying acceptable alternative nematode management tactics for use on turfgrasses. Two field experiments were conducted to evaluate the effectiveness of repeated applications of several commercially available nematicides and root biostimulants for reducing population densities of plant-parasitic nematodes and (or) promoting health of bermudagrass in nematode-infested soil. One experimental site was infested with Hoplolaimus galeatus and Trichodorus obtusus, the second with Belonolaimus longicaudatus. In both trials, none of the experimental treatments reduced population densities (P ≤ 0.1) of plant-parasitic nematodes, or consistently promoted turf visual performance or turf root production. Nematologists with responsibility to advise turf managers regarding nematode management should thoroughly investigate the validity of product claims before advising clientele in their use.     

Slit Injection of 1,3-Dichloropropene for Management of Belonolaimus longicaudatus on Established Bermudagrass

Belonolaimus longicaudatus is a serious problem on bermudagrass, a common warm-season turfgrass, in Florida. The cancellation of organophosphate nematicides necessitates that new management tools be identified for use on sports turf. Postplant application of 1,3-dichloropropene (1,3-D) on bermudagrass was evaluated for management of B. longicaudatus on golf course fairways and driving ranges. A series of 10 experiments were conducted to evaluate the effectiveness of 1,3-D in reducing population densities of B. longicaudatus and enhancing bermudagrass recovery from nematode damage. In 5 of 10 experiments, 1,3-D injected at 46.8 liters/ha was effective in reducing population densities of B. longicaudatus (P < 0.05) compared to untreated plots 2 to 4 weeks after treatment. One month after treatment, population densities of B. longicaudatus ranged from 59% to 97% of those in untreated plots. Nematode suppression generally lasted 2 months or less. Turf visual performance was improved following injection with 1,3-D (P < 0.05) over untreated plots when other factors were not limiting. Turf root development also was enhanced following injection with 1,3-D. Postplant injection of 1,3-D could be a useful nematode management tool for certain sports turf applications.     

Field Efficacy of Furfural as a Nematicide on Turf

A commercial formulation of furfural was recently launched in the United States as a turfgrass nematicide. Three field trials evaluated efficacy of this commercial formulation on dwarf bermudagrass putting greens infested primarily with Belonolaimus longicaudatus, Meloidogyne graminis, or both these nematodes, and in some cases with Mesocriconema ornatum or Helicotylenchus pseudorobustus. In all these trials, furfural improved turf health but did not reduce population densities of B. longicaudatus, M. graminis, or the other plant-parasitic nematodes present. In two additional field trials, efficacy of furfural at increasing depths in the soil profile (0 to 5 cm, 5 to 10 cm, and 10 to 15 cm) against B. longicaudatus on bermudagrass was evaluated. Reduction in population density of B. longicaudatus was observed in furfural-treated plots for depths below 5 cm on several dates during both trials. However, no differences in population densities of B. longicaudatus were observed between the furfural-treated plots and the untreated control for soil depth of 0 to 5 cm during either trial. These results indicate that furfural applications can improve health of nematode-infested turf and can reduce population density of plant-parasitic nematodes in turf systems. Although the degree to which turf improvement is directly caused by nematicidal effects is still unclear, furfural does appear to be a useful nematode management tool for turf.     

Host Status of 'SeaIsle 1' Seashore Paspalum (Paspalum vaginatum) to Belonolaimus longicaudatus and Hoplolaimus galeatus

Belonolaimus longicaudatus and Hoplolaimus galeatus are considered among the most damaging pathogens of turfgrasses in Florida. However, the host status of seashore paspalum (Paspalum vaginatum) is unknown. Glasshouse experiments were performed in 2002 and 2003 to determine the tolerance of ''SeaIsle 1'' seashore paspalum to a population of B. longicaudatus and a population of H. galeatus, and to compare to ''Tifdwarf'' bermudagrass for differences. Both nematode species reproduced well on either grass, but only B. longicaudatus consistently reduced root growth as measured by root length. Belonolaimus longicaudatus reduced root growth (P ≤ 0.05) by 35% to 45% at 120 days after inoculation on both grasses. In 2003, higher inoculum levels of H. galeatus reduced root growth (P ≤ 0.05) by 19.4% in seashore paspalum and by 14% in bermudagrass after 60 and 120 days of exposure, respectively. Percentage reductions in root length caused by H. galeatus and B. longicaudatus indicated no differences between grass species, although Tifdwarf bermudagrass supported higher soil population densities of both nematodes than SeaIsle 1 seashore paspalum.     

Effects of a Commercial Formulation of Paecilomyces lilacinus Strain 251 on Overseeded Bermudagrass Infested with Belonolaimus longicaudatus

Belonolaimus longicaudatus is an important parasite of both warm-season bermudagrass and winter overseed grasses used on golf courses in the southeastern United States. Field trials were conducted to study the effects of a commercial formulation of Paecilomyces lilacinus strain 251 applied to overseed grasses during the winter and early spring on population density of B. longicaudatus and bermudagrass health in late spring after bermudagrass broke dormancy. These studies found that P. lilacinus reduced numbers of B. longicaudatus in most cases, but not below damaging levels. Multiple applications of 1 × 10¹⁰ spores/m² were generally more effective than 2 × 10¹⁰ spores/m² in reducing nematode numbers and improving turf roots. These results indicate that application of this formulation of P. lilacinus strain 251 to overseeded turf in the spring may be a useful integrated pest management tool for B. longicaudatus on bermudagrass, but is not sufficient as a stand-alone nematode management tactic.     

Effects of a Commercial Formulation of Bacillus firmus I-1582 on Golf Course Bermudagrass Infested with Belonolaimus longicaudatus

One of the primary pests of bermudagrass (Cynodon spp.) on golf courses in the southeastern United States is Belonolaimus longicaudatus (sting nematode). In 2011, a commercial formulation of Bacillus firmus I-1582, Nortica 5WG, was launched in the United States for management of plant-parasitic nematodes on turfgrasses. To test the efficacy of late winter/early spring application of this biopesticide on B. longicaudatus, two field trials in 2009 compared B. firmus with fenamiphos and untreated control treatments. In 2011, two additional field trials compared treatment with B. firmus with untreated control only. These trials measured treatment effects on the population density of B. longicaudatus, turf root length, and turf percent green cover. In all four trials, treatment with B. firmus improved root length and decreased numbers of B. longicaudatus in contrast to the untreated. These results indicate that late winter/early spring application of B. firmus is an effective biopesticide treatment for management of B. longicaudatus on golf course bermudagrass.     

Yield Reduction and Root Damage to Cotton Induced by Belonolaimus longicaudatus

Sting nematode (Belonolaimus longicaudatus) is recognized as a pathogen of cotton (Gossypium hirsutum), but the expected damage from a given population density of this nematode has not been determined. The objective of this study was to quantify the effects of increasing initial population densities (Pi) of B. longicaudatus on cotton yield and root mass. In a field plot study, nematicide application and cropping history were used to obtain a wide range of Pi values. Cotton yields were regressed on Pi density of B. longicaudatus to quantify yield losses in the field. In controlled environmental chambers, cotton was grown in soil infested with increasing Pi''s of B. longicaudatus. After 40 days, root systems were collected, scanned on a desktop scanner, and root lengths were measured. Root lengths were regressed on inoculation density of B. longicaudatus to quantify reductions in the root systems. In the field, high Pi''s (>100 nematodes/130 cm³ of soil) reduced yields to near zero. In controlled environmental chamber studies, as few as 10 B. longicaudatus/130 cm³ of soil caused a 39% reduction in fine cotton roots, and 60 B. longicaudatus/130 cm³ of soil caused a 70% reduction. These results suggest that B. longicaudatus can cause significant damage to cotton at low population densities, whereas at higher densities crop failure can result.     

Effects and Dynamics of a Nematode Community on Soybean

The relationships between densities of all members of a plant-parasitic nematode community and yield of ''Davis'' soybean and between final and preplant population levels were examined in small plots on sandy soils in north-central Florida. Plant-parasitic nematodes present in the community included Belonolaimus longicaudatus, Criconemella sphaerocephala, Meloidogyne incognita, Paratrichodorus minor, Pratylenchus brachyurus, and Xiphinema sp. Plant growth, including stand count, soybean yield (kg/ha), and size of young plants, was occasionally inversely correlated (P ≤ 0.05) with densities of B. longicaudatus or P. brachyurus, but not with densities of other species or with a range of soil variables. The nature of this relationship varied with season, with more severe stand losses noted during 1987 than in 1988. Final population densities (Pf) of most nematode species showed significant (P ≤ 0.05) linear relationships to densities measured at planting or earlier (Pi). These relationships were stronger (higher r²) with the ectoparasite B. longicaudatus than with the endoparasites M. incognita and P. brachyurus. Criconemella sphaerocephala declined under soybean cultivation, reaching levels near zero after two seasons. A quadratic model showed an improvement (P ≤ 0.05) over the linear model in describing the relationship between Pf and Pi measured at planting for B. longicaudatus, and gave a better indication of the leveling off of Pf at high values of Pi.     

Effects and Dynamics of a Nematode Community on Maize

Relationships between nematode density and yield and between final and preplant population levels were examined in small maize plots on sandy soils in north-central Florida. Plant-parasitic nematodes present in the community included Belonolaimus longicaudatus, Criconemella sphaerocephala, Meloidogyne incognita, Paratrichodorus minor, Pratylenchus brachyurus, and a Xiphinema sp. Plant growth--including stand count, grain yield, stalk weight, and size of young plants--often was inversely correlated (P ≤ 0.05) with densities of B. longicaudatus and occasionally with P. brachyurus, but not with densities of other species or with a range of soil variables. More severe losses in grain yields from B. longicaudatus occurred in 1987 than in 1988, although mean preplant nematode densities in February were similar in both years (4.4 vs. 3.9/100 cm³ soil). Final population densities of most nematode species were linearly related (P ≤ 0.05) to densities measured at planting or earlier. These relationships were stronger (higher r²) with the ectoparasites B. longicaudatus and C. sphaerocephala than with the endoparasites M. incognita and P. brachyurus. No significant correlations were found between population densities of different nematode species.     

Host responses and metabolic profiles of wood components in Dutch elm hybrids with a contrasting tolerance to Dutch elm disease

Background and Aims

Changes occurring in the macromolecular traits of cell wall components in elm wood following attack by Ophiostoma novo-ulmi, the causative agent of Dutch elm disease (DED), are poorly understood. The purpose of this study was to compare host responses and the metabolic profiles of wood components for two Dutch elm (Ulmus) hybrids, ‘Groeneveld’ (a susceptible clone) and ‘Dodoens’ (a tolerant clone), that have contrasting survival strategies upon infection with the current prevalent strain of DED.

Methods

Ten-year-old plants of the hybrid elms were inoculated with O. novo-ulmi ssp. americana × novo-ulmi. Measurements were made of the content of main cell wall components and extractives, lignin monomer composition, macromolecular traits of cellulose and neutral saccharide composition.

Key Results

Upon infection, medium molecular weight macromolecules of cellulose were degraded in both the susceptible and tolerant elm hybrids, resulting in the occurrence of secondary cell wall ruptures and cracks in the vessels, but rarely in the fibres. The ¹³C nuclear magnetic resonance spectra revealed that loss of crystalline and non-crystalline cellulose regions occurred in parallel. The rate of cellulose degradation was influenced by the syringyl:guaiacyl ratio in lignin. Both hybrids commonly responded to the medium molecular weight cellulose degradation with the biosynthesis of high molecular weight macromolecules of cellulose, resulting in a significant increase in values for the degree of polymerization and polydispersity. Other responses of the hybrids included an increase in lignin content, a decrease in relative proportions of d-glucose, and an increase in proportions of d-xylose. Differential responses between the hybrids were found in the syringyl:guaiacyl ratio in lignin.

Conclusions

In susceptible ‘Groeneveld’ plants, syringyl-rich lignin provided a far greater degree of protection from cellulose degradation than in ‘Dodoens’, but only guaiacyl-rich lignin in ‘Dodoens’ plants was involved in successful defence against the fungus. This finding was confirmed by the associations of vanillin and vanillic acid with the DED-tolerant ‘Dodoens’ plants in a multivariate analysis of wood traits.     

Influence of Belonolaimus longicaudatus on Nitrate Leaching in Turf

Experiments were conducted to quantify the effects of the sting nematode (Belonolaimus longicaudatus) on root reductions and quantity of nitrate (NO₃ ⁻) leached from ‘Tifdwarf’ bermudagrass in lysimeters. Forty lysimeters were planted with ‘Tifdwarf’ bermudagrass, of which 20 were inoculated with B. longicaudatus and 20 were noninoculated. Root length was compared between treatments at six, 12, and 18 weeks after initiation of the experiments. Turf was fertilized every three weeks, and leaching events were simulated at 21 and 42-day intervals in trial one and trial two, respectively. Leachate was collected, and the quantity of NO₃ ⁻ leached was compared between treatments. Root reductions were observed in lysimeters inoculated with B. longicaudatus at all evaluation dates. Quantity of NO₃ ⁻ leached was greater in inoculated lysimeters at the 18-week evaluation during both trials. This study indicates that nematode damage to turf roots limits root vigor and N uptake, thereby increasing nitrate leaching, adding to water quality concerns.     

Host Status of Different Potato (Solanum tuberosum) Varieties and Hatching in Root Diffusates of Globodera ellingtonae

Globodera ellingtonae was detected in Oregon in 2008. In order to make decisions regarding the regulation of this nematode, knowledge of its biology is required. We determined the host status of a diversity of potato (Solanum tuberosum) varieties in soil-based experiments and identified hatching stimulants in in vitro hatching assays. ‘Russet Burbank,’ ‘Desiree,’ ‘Modac,’ ‘Norland,’ ‘Umatilla,’ and ‘Yukon Gold’ were good hosts (RF > 14) for G. ellingtonae. Potato varieties ‘Maris Piper,’ ‘Atlantic,’ and ‘Satina,’ all which contain the Ro1 gene that confers resistance to G. rostochiensis, were not hosts for G. ellingtonae. In in vitro hatching assays, G. ellingtonae hatched readily in the presence of diffusates from potato (PRD) and tomato (Solanum lycopersicum; TRD). Egg hatch occurred in an average of between 87% and 90% of exposed cysts, with an average of between 144 and 164 juveniles emerging per cyst, from PRD- and TRD-treated cysts, respectively. This nematode hatched rapidly in the presence of PRD and TRD, with at least 66% of total hatch occurring by day 3 of exposure. There was no dose-response of egg hatch to concentrations of PRD or TRD ranging from 1:5 to 1:100 diffusate to water. When G. ellingtonae was exposed to root diffusates from 21 different plants, hatch occurred in 0% to 70% of exposed cysts, with an average of between 0 to 27 juveniles emerging per cyst. When root diffusate-exposed cysts were subsequently transferred to PRD to test viability, root diffusates from arugula (Eruca sativa), sudangrass (Sorghum bicolor subsp. drummondii), and common vetch (Vicia sativa) continued to inhibit egg hatch compared with the other root diffusates or water in which hatch occurred readily (60 to 182 juveniles emerging per cyst). Previously known hatching stimulants of G. rostochiensis and G. pallida, sodium metavanadate, sodium orthovanadate, and sodium thiocyanate, stimulated some egg hatch. Although, Globodera ellingtonae hatched readily in PRD and TRD and reproduced on potato, the pathogenicity of this nematode on potato remains to be determined.     

Relationships Between Tolerance and Resistance to Meloidogyne incognita in Cotton

The southern root-knot nematode, Meloidogyne incognita, is the most damaging pathogen of cotton in the United States, and both resistance and tolerance to M. incognita could be valuable management approaches. Our objectives were to evaluate advanced cotton breeding lines for resistance and tolerance to M. incognita and to determine if a relationship between resistance and tolerance exists. Reproduction of M. incognita was evaluated on 17 breeding lines, a susceptible control (Delta and Pine Land DP5415), and a resistant control (M-120) in two greenhouse trials with six replications in a randomized complete block design. Two-week-old seedlings were inoculated with 8,000 M. incognita eggs and assessed for egg production 8 weeks later. Reproduction on the resistant control was only 10% of that on the susceptible control. Eight breeding lines supported 45% to 57% less (P <= 0.05) nematode reproduction than the susceptible control, and none of them were as resistant as M-120. Yield was determined in 2001 and 2002 in fumigated (1,3-dichloropropene at 56 liters/ha) and nonfumigated plots in a strip-plot design with three replications in a field naturally infested with M. incognita. Yield suppression caused by nematode infection differed among genotypes (P ≤ 0.05 for genotype × fumigation interaction). Six genotypes in 2001 and nine in 2002 were tolerant to M. incognita based on no difference in yield between the fumigated and nonfumigated plots (P ≥ 0.10). However, only three genotypes had no significant yield suppression in both years, of which two also were resistant to M. incognita. Regression analysis indicated that yield suppression decreased linearly as nematode resistance increased.     

Population Dynamics of Plant Nematodes in Cultivated Soil: Effect of Sod-based Rotations in Tifton Sandy Loam

In an 8-year sod-based rotation study, nematode population densities varied with different row-crop sequences and grass sods. In continuous row-crop rotations (cotton-corn-peanut), cotton and corn favored rapid increase of Belonolaimus longicaudatus and Trichodorus christiei. Numbers of Pratylenchus brachyurus were quite variable on all crops. Peanuts favored an increase of Criconemoides ornatum but suppressed the other three species. ''Coastal'' bermudagrass supported more than twice the number of B. longicaudatus than did ''Pensacola'' bahiagrass. Numbers of T. christiei and P. brachyurus also were larger on bermudagrass than on bahiagrass. Numbers of C. ornatum were largest in row-crop sequence culture. Average numbers of B. longicaudatus, T. christiei, and P. brachyurus in a sod-based, 3-years of row-crop sequence were smallest when cotton and corn did not follow each other. These nematodes were further suppressed when the sequence corn-peanut-cotton followed bahiagrass. Numbers of C. ornatum were smallest when corn and cotton followed each other, except after 3 years of bahiagrass. Nematode populations were less influenced by row-crop sequence following bermudagrass than they were following bahiagrass.     

Dynamics of Belonolaimus longicaudatus Parasitism on a Susceptible St. Augustinegrass Host

St. Augustinegrass (Stenotaphrum secundatum) cv FX-313 was used as a model laboratory host for monitoring population growth of the sting nematode, Belonolaimus longicaudatus, and for quantifying the effects of sting nematode parasitism on host performance in two samples of autoclaved native Margate fine sand with contrasting amounts of organic matter (OM = 7.9% and 3.8%). Following inoculation with 50 Belonolaimus longicaudatus per pot, nematodes peaked at a mean of 2,139 nematodes per pot 84 days after inoculation, remained stable through 168 days at 2,064 nematodes per pot, and declined at 210 days. The relative numbers of juveniles and adults demonstrated senescence after 84 days. Root dry weight of nematode-inoculated plants increased briefly to an apparent equilibrium 84 days after inoculation, whereas root weights of uninoculated controls continued to increase, exceeding those of inoculated plants from 84 to 210 days (P < 0.01). At 210 days, uninoculated plants had 227% the root dry weight of inoculated plants. Transpiration of FX-313 was reduced by nematodes (P < 0.0001) at 84 and 126 days after inoculation; reduction was first observed at 42 days and last observed 168 days after inoculation (P < 0.05). OM content affected all plant performance variables at multiple dates, and generally there were no inoculation x OM content interactions. OM content had no effect on nematode numbers per pot, although there was a slight (P < 0.05) increase in the number of nematodes per gram root dry weight in the low-OM soil compared with the high-OM soil.     

Saline Irrigation Affects Belonolaimus longicaudatus and Hoplolaimus galeatus on Seashore Paspalum

Seashore paspalum (Paspalum vaginatum) has great potential for use in salt-affected turfgrass sites. Use of this grass on golf courses, athletic fields, and lawns in subtropical coastal areas may aid in conservation of freshwater resources. Belonolaimus longicaudatus and Hoplolaimus galeatus are considered among the most damaging root pathogens of turfgrasses in Florida. Glasshouse experiments were performed in 2002 and 2003 to examine the effects of increasing levels of irrigation salinity on B. longicaudatus and H. galeatus. Irrigation treatments were formulated by concentrating deionized water to six salinity levels (0, 5, 10, 15, 20, and 25 dS/m). Final population densities of H. galeatus followed a negative linear regression (r² = 0.92 and 0.83; P <= 0.01) with increasing salinity levels. Final population densities of B. longicaudatus were quadratically (r² = 0.72 and 0.78; P <= 0.01) related to increasing salinity levels from 0 to 25 dS/m. An increase in population densities of B. longicaudatus was observed at moderate salinity levels (10 and 15 dS/m) compared to 0 dS/m. Root-length comparisons revealed that B. longicaudatus caused root stunting at low salinity levels, 0 to 10 dS/m, but roots were not affected at 15 to 25 dS/m. These results indicate that the ability of B. longicaudatus to feed and stunt root growth was negatively affected at salinity levels of 15 dS/m and above.     

Sugar composition of the pectic polysaccharides of charophytes,the closest algal relatives of land-plants: presence of 3-O-methyl-d-galactose residues

Background and Aims During evolution, plants have acquired and/or lost diverse sugar residues as cell-wall constituents. Of particular interest are primordial cell-wall features that existed, and in some cases abruptly changed, during the momentous step whereby land-plants arose from charophytic algal ancestors.Methods Polysaccharides were extracted from four charophyte orders [Chlorokybales (Chlorokybus atmophyticus), Klebsormidiales (Klebsormidium fluitans, K. subtile), Charales (Chara vulgaris, Nitella flexilis), Coleochaetales (Coleochaete scutata)] and an early-diverging land-plant (Anthoceros agrestis). ‘Pectins’ and ‘hemicelluloses’, operationally defined as extractable in oxalate (100 °C) and 6 m NaOH (37 °C), respectively, were acid- or Driselase-hydrolysed, and the monosaccharides analysed chromatographically. One unusual monosaccharide, ‘U’, was characterized by ¹H/¹³C-nuclear magnetic resonance spectroscopy and also enzymically.Key Results ‘U’ was identified as 3-O-methyl-d-galactose (3-MeGal). All pectins, except in Klebsormidium, contained acid- and Driselase-releasable galacturonate, suggesting homogalacturonan. All pectins, without exception, released rhamnose and galactose on acid hydrolysis; however, only in ‘higher’ charophytes (Charales, Coleochaetales) and Anthoceros were these sugars also efficiently released by Driselase, suggesting rhamnogalacturonan-I. Pectins of ‘higher’ charophytes, especially Chara, contained little arabinose, instead possessing 3-MeGal. Anthoceros hemicelluloses were rich in glucose, xylose, galactose and arabinose (suggesting xyloglucan and arabinoxylan), none of which was consistently present in charophyte hemicelluloses.Conclusions Homogalacturonan is an ancient streptophyte feature, albeit secondarily lost in Klebsormidium. When conquering the land, the first embryophytes already possessed rhamnogalacturonan-I. In contrast, charophyte and land-plant hemicelluloses differ substantially, indicating major changes during terrestrialization. The presence of 3-MeGal in charophytes and lycophytes but not in the ‘intervening’ bryophytes confirms that cell-wall chemistry changed drastically between major phylogenetic grades.